Influence of Various Parameters on the Response Factors of the Evaporative Light Scattering Detector for a Number of Non-Volatile Compounds

Abstract

We have investigated the influence of the most important operation parameters of the evaporative light scattering detector (ELSD) on its response factors. When the detector is operated under proper experimental conditions, the repeatability of the response factor is around 1%. The response factors and the signal to noise ratio are maximum for a certain flow rate of scavenger gas, which depends much on the exact dimensions of the nebulizer. The temperature of the drift tube has no effect, as long as the vapor pressure of the solvent is larger than ca 200 torrs. The nature of the mobile phase has some effect, related to the surface tension and viscosity of the solvent used. The most important factor, however, is the nebulizer itself. Replacing the nebulizer by another one, made with the same tubes, or changing slightly the position of the liquid nozzle in the gas nozzle may change markedly the response as well as its relationship with sample size. The peak area increases exponentially with increasing sample size. but the exponent depends very much on the exact design of the nebulizer. Similar response factors are obtained for fatty acid methyl esters, triglycerides, sugars, polynuclear aromatic hydrocarbons and polystyrene.